Fuel metering device



Sept 15 1942' s. Hx-:RsEY Erm. 2,295,656).

FUEL' METERING DEvIc Filed April 24. 194o ATTORNEY Patented Sept, i5, i942 Donald S. Hersey, West Hartford, and Arthur E. Smith, Manchester, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application April 24, 1940, Serial No. 331,448

(Cl. 26h-18) 1 Claim.

This invention relates to improvements in engine fuel metering controls and has particular reference to an improved fuel metering device for an internal combustion engine utilizing eX- plosive charges formed by evaporating fuel in the intake air.

An object of the invention resides in the provision of an improved fuel metering device of the character indicated which is operative to meter a standard fuel to the engine at all times during engine operation and to meter an auxiliary fuel to the engine under certain predetermined engine operating conditions.

A somewhat more specic object resides in the provision of an improved fuel metering device of the character indicated which is operative to supply a regulated quantity of detonation reducing fuel modifying substance to the engine under engine operating conditions where detonation is likely to occur.

A still further object resides in the provision in an improved fuel metering device of the character indicated of manually controllable means for causing an injection of the auxiliary fuel into the engine fuel supply as the operator may desire, for instance at such time as there appers to be a condition of ice formation in the engine intake.

Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawing, in which like reference numerals are used to designate similar parts throughout, there is illustrated a suitable mechanical embodiment of a portion of an engine intake and a fuel metering device, for the purpose of disclosing the invention. The drawing, however, is for the purpose of illustration only and is not to be taken as limiting the invention since it will be apparent to those skilled in the art that various changes in the illustrated construction may be resorted to without in any way exceeding the scope of the invention.

In the accompanying drawing, the single figure is a longitudinal sectional view of a portion of an engine intake with a fuel metering device,

constructed according to the invention, applied thereto, the drawing being largely diagrammatic in character.

as is well known to those skilled in the operation of internal combustion engines, detonation of the fuel charges in the engine cylinders tends to occur only under particular engine operating conditions and if the fuel used is well suited to the engine, detonation, if it occurs at all, will usually occur only in the upper portion of the engine power range. Even with the best fuel, however, in order to obtain good fuel economy it is necessary to operate the engine near the detonation point in the upper portion oi thel power range and it frequently happens that detonation occurs when the engine reaches the upper part of the range.V For example, in the case of an airplane engine, in order to obtain good fuel economy in the cruising range it is detonation would occur to suppress the detonation under those particular operating conditions. If anvengine is so adjusted that it will run on ordinary. aviation gasoline without detonation except inthe take-off portion of the power range, a small quantity of fuel ingredient of high antidetonation characteristics supplied to the engine only during the take-off period will provide detonation free engine operation and excellent fuel economy as the take-off operation of the engine is a very small fractional; part of its total ora tion. It has been found that an ingredient coin` prising a mixture of aniline and alcohol is 'very effective in eliminating detonation in thoseportions of the power range in which detonation would occur with the ordinary engine fuel and that, by adjusting the engine so 'that detonation `would occur in the talee-ofi' portion of the range,

forexample, on the ordinary i'uel and then sup= plying additional anti-detonating fuel, such asV the aniline and alcohol mixture, to the engine during take-off, greatly improved fuel economy and detonation free operation. is, obtained. Instead ofthe additional `fuel, a fuel modifying substance, such as tetra-ethyl lead, or a combination of the two may be used, if desired. it is es-l sential, however, that the additional material should be automatically supplied to the engine whenever the power output of the engine exceeds the value at which the` engine-'will operate without detonation on the ordinary iuei, as the operator of the engine may not always be able to detectthe detonation point supply the adu ditional material in 'tir avoid the heginning of detonation. 'it has round that once ina direction toppen-the valve 20 the correspending pressure differential on the economiser vthe spring 96 andopen the valve 92 to admit additional fuel through thisvalve from the space the spring is overcome and the valve iiE begins to open, auxiliary fuel will flow from the Y i line H0 through the valve |08, and channel U8, diaphragme will become'sumcient to compress below the diaphragm 08 to the space in the,

chamber 28 above the diaphragm 4B and below the partition 00 and from thence throughthe `channel 50 to the fuel nozzle 22.

For a more detailed description of the con struction and operation of a suitable fuel metering device, idling range control and economizer filed November 3, 1939', by Guy E. Beardsley, Jr. The lower portion of "the chamber 20 is sealed i off by a transverse diaphragm 88 and Vfrom this l diaphragm a shaft |00 extends downwardly in l the chamber to'a second :diaphragm |02 below which the end of the shaft |00 rests upon a compression spring |04 the lower end of which is carried upon an" adjustable abutment |00. Between the diaphragms 98 and I 02 the stemcarries a valve gate |00 which cooperates with a seat formed around an vaperture in a transverse par tition H0 to constitute a valve generally indicated at |I2. A secondary fuel line Ill connects with a channel H6 leading into the space between the partition"||0 and-.the diaphragm 02 and a channel ll'leadsthrough a conduit |20 including a restricted orifice |22 from the space between the partition H0 and the diaphragm 08 to the channel 50. 4 The pressure on the fuel in the space in the chamber 26 below the diaphragm -48 will be' transmitted through the 'passage 12 to the space in the lower chamber 28 between the diaphragms se and ss. Y

- The pressure on the fuel in the line 50, as long -as there is no fuel iiowing in the line H8, is

transmitted through the passages H8 and |20. 'Ihe pressures acting on the diaphragm |02 balance the pressures acting on the valve |08 in a manner similar to the way the pressures on the valve 30 are balanced by the pressures ,on the diaphragm. 04 of the main fuel supply except that in this case, the pressure on the area of thestem |00 not have a force opposing it.' but in effect adds to the pressure acting on the lower side ofthe diaphragm 98. It will thus be seen the valve |00 is the product of the area of diaphragm 98 and the diierence in pressures acting on theA diaphragm 88 which diierence. as has been pointed out above, is the same as the difference in pressures acting upon the diaphragm 48 and which in turn is the same as the difference in the pressures-acting upon the diaphragm 08. 'Ihe force on the diaphragm 08 tends to open the valve Y|08 and is opposed by -tlie spring |04 supported by the adjustable abutment |00. The abutment `|05 is adjusted to maintain the valve |08 closed until the dierence in the pressures acting on the diaphragm 90 exceeds a predetermined value. As this dierential pressure is the must bexopened to maintain that differential pressure. The dierence between the pressures vacting upon the diaphragm i6 and the pressures acting upon the diaphragm 98 in these higher values will be accounted for by the pressure drop across the orice I 22. This drop will, of course. 4

be substantially proportionate to the increase in' differential pressure above the predetermined amount so that the fuel flow will be accordingly proportioned to this increase in differential pressure-and hence to the increase in airflow.

If desired, the spring |00 may be so adjusted and the value of spring 0S of the economizer 18 so chosen that the valve ||2 willopen to supply auxiliary'fuel tothe engine when the economizer valve 92 opens to richen the engine fuel for extremely high power operating conditions. It is not necessary, however, that-there be any definite cooperation between the economizer and the auxiliary fluid supply.

lThe auxiliary fuel and substance mail',l if desired, be so chosen that the economizer may be dispensed with and the auxiliary valve |03 relied upon to perform the en tiro functions of supplying additional fuel for 'economiser action and for supplying an antidetonating'substance.

-Whenever auxiliary fuel is supplied to the engine it is mixed with the main fuel supply`before reaching the carburetor discharge jet or the inf" jection nozzle in order that the detonationrel ducing fluid may be distributed evenly with the main fuel to all of the engine cylinders. With this arrangement, ifethere is a good distribution of the main fuel, there will be an equally good f distribution of the mixture of the mein fuel and .that the flow responsive force tending to move same as the differential pressure of the airow measuring mechanism, it is at once apparent that the'auxiliary uid and thedetonation inhibiting' tendency will be applied equally to all of the engine cylinders.

Any suitable manually actuatablel means may be provided to open the valve |08 against the valve closing force of the spring it when it is desired to inject .the auxiliary fuel for de-icing the intake passages or for other purposes, when the engine is not operating-at suiiicient power to cause an automatic injection of said auxiliary fuel in sucient quantity. c

In the arrangement illustrated,r a shaft |23 projects through the casing 20 and causes Vat its inner end a cam |25 which is positioned over the upper end of the stem |00. A lever arm |20 is connected to the end of the shaft |23 outside of the casing 2t and a manually operable linkage, as indicated at |20, is connected to the free end of the lever to rotate the shaft |23 under manual actuation and cause the cam |25 to bear against the upper end of the stem i0@ and open thevalve.

While a suitable mechanical arrangement has antidetonating i changes in the illustrated arrangement may be resorted to as come within the scope of the subioined claims.

Having now described the invention so that others skilled in the art may clearly understand the saine, what it is desired to secure by Letters Patent is as follows:

An engine fuel supply system comprising, an air intake, a venturi in said intake for measuring the quantity of air owing theretllrough, a fuel supply line, means responsive to the air flow through said venturi and the fuel flow through said supply line for proportioning the quantity ol fuel to the quantity of air, a nozzle for injecting said fuel into the air stream, an economizer device for increasing the proportion of fuel in the fuel-air mixture whenever the rate of fuel ow exceeds a predetermined value, means for injecting an anti-detonation ingredient into the fuel supply ahead of said nozzle, means for Withholding said ingredient until the fuel flow rate reaches a predetermined value, and valve means actuated by the Huid pressure of said fuel for proportioning the quantity of said ingredient to the quantityf fuel after said predetermined rate of fuel flow has been reached.

DONALD S. HERSEY.

ARTHUR E. SMITIL, 

